auget

An auget is a small-diameter tube or channel that runs from the main charge chamber of a blast hole to an accessible point on the gallery wall or borehole collar, where the slow match or detonating cord can be connected and ignited. It allows the fuse to reach the explosive load without requiring the operator to insert material directly into the charge itself.

In underground mining practice, augets are typically drilled as auxiliary holes at a slight angle from the main blast hole, or formed as part of the borehole design when charges are being prepared. The auget must be clear of obstructions and positioned so the fuse material lies protected from accidental disturbance during loading operations. The diameter is kept small, usually between 6 and 12 millimetres, sufficient only for the slow match or cord to pass through.

Construction and materials

The auget itself may be a simple drilled hole through rock, or it can be lined with a metal or plastic tube to protect the fuse and prevent blockage. When installed in muddy or wet ground, a rigid tube is essential to maintain the connection. The tube is often filled with dry sand or graphite powder to prevent moisture reaching the fuse and to reduce friction as the match is inserted.

The term is most common in British and European mining nomenclature, particularly in coal mines and metalliferous operations where controlled blasting underground was routine. The auget represents a safety principle: the slow match or detonator sits outside the borehole until the last moment, reducing the risk of accidental detonation during preparation and loading. Blocked or damaged augets are a known cause of misfires and are checked carefully before blasting operations commence.